Photo/electrochemical splitting of water to hydrogen (H 2 ) fuel is a sustainable way of meeting our energy demands at no environmental cost, but significant challenges remain: for example, the ...sluggish anodic reaction imposes a considerable overpotential requirement. By contrast, urea electrolysis offers the prospect of energy-saving H 2 production together with urea-rich wastewater purification, whereas the lack of inexpensive and efficient urea oxidation reaction (UOR) catalysts places constraints on the development of this technique. Here we report a porous rod-like NiMoO 4 with high oxidation states of the metal elements enabling highly efficient UOR electrocatalysis, which can be readily produced through annealing solid NiMoO 4 · x H 2 O as a starting precursor in Ar. This precursor gives the derived Ni/NiO/MoO x nanocomposite when switching the shielding gas from Ar to H 2 /Ar, exhibiting platinum-like activity for the hydrogen evolution reaction (HER) in alkaline electrolytes. Assembling an electrolytic cell using our developed UOR and HER catalysts as the anode and cathode can provide a current density of 10 milliamperes per square centimeter at a cell voltage of mere 1.38 volts, as well as remarkable operational stability, representing the best yet reported noble-metal-free urea electrolyser. Our results demonstrate the potential of nickel–molybdenum-based materials as efficient electrode catalysts for urea electrolysers that promises cost-effective and energy-saving H 2 production.
The anode oxygen evolution reaction (OER) is known to largely limit the efficiency of electrolyzers owing to its sluggish kinetics. While crystalline metal oxides are promising as OER catalysts, ...their amorphous phases also show high activities. Efforts to produce amorphous metal oxides have progressed slowly, and how an amorphous structure benefits the catalytic performances remains elusive. Now the first scalable synthesis of amorphous NiFeMo oxide (up to 515 g in one batch) is presented with homogeneous elemental distribution via a facile supersaturated co‐precipitation method. In contrast to its crystalline counterpart, amorphous NiFeMo oxide undergoes a faster surface self‐reconstruction process during OER, forming a metal oxy(hydroxide) active layer with rich oxygen vacancies, leading to superior OER activity (280 mV overpotential at 10 mA cm−2 in 0.1 m KOH). This opens up the potential of fast, facile, and scale‐up production of amorphous metal oxides for high‐performance OER catalysts.
Amorphous NiFeMo oxide (up to 515 g one batch) with homogeneous elemental distribution was synthesized through a facile supersaturated co‐precipitation method. The amorphous NiFeMo oxide undergoes rapid surface self‐reconstruction during OER that forms a metal oxy(hydroxide) active layer with oxygen vacancies, enabling efficient OER catalysis.
Salicylic acid (SA), an essential regulator of plant defense, is derived from chorismate via either the phenylalanine ammonia lyase (PAL) or the isochorismate synthase (ICS) catalyzed steps. The ICS ...pathway is thought to be the primary contributor of defense-related SA, at least in Arabidopsis. We investigated the relative contributions of PAL and ICS to defenserelated SA accumulation in soybean (Glycine max).
Soybean plants silenced for five PAL isoforms or two ICS isoforms were analyzed for SA concentrations and SA-derived defense responses to the hemibiotrophic pathogens Pseudomonas syringae and Phytophthora sojae.
We show that, unlike in Arabidopsis, PAL and ICS pathways are equally important for pathogen-induced SA biosynthesis in soybean. Knock-down of either pathway shuts down SA biosynthesis and abrogates pathogen resistance. Moreover, unlike in Arabidopsis, pathogen infection is associated with the suppression of ICS gene expression. Pathogen-induced biosynthesis of SA via the PAL pathway correlates inversely with phenylalanine concentrations. Although infections with either virulent or avirulent strains of the pathogens increase SA concentrations, resistance protein-mediated response to avirulent P. sojae strains may function in an SA-independent manner.
These results show that PAL- and ICS-catalyzed reactions function cooperatively in soybean defense and highlight the importance of PAL in pathogen-induced SA biosynthesis.
Abstract
Nanoparticles-based glues have recently been shown with substantial potential for hydrogel adhesion. Nevertheless, the transformative advance in hydrogel-based application places great ...challenges on the rapidity, robustness, and universality of achieving hydrogel adhesion, which are rarely accommodated by existing nanoparticles-based glues. Herein, we design a type of nanohesives based on the modulation of hydrogel mechanics and the surface chemical activation of nanoparticles. The nanohesives can form robust hydrogel adhesion in seconds, to the surface of arbitrary engineering solids and biological tissues without any surface pre-treatments. A representative application of hydrogel machine demonstrates the tough and compliant adhesion between dynamic tissues and sensors via nanohesives, guaranteeing accurate and stable blood flow monitoring in vivo. Combined with their biocompatibility and inherent antimicrobial properties, the nanohesives provide a promising strategy in the field of hydrogel based engineering.
Portal vein tumor thrombosis (PVTT) is a significant risk factor for metastasis in hepatocellular carcinoma (HCC) patients and is therefore associated with poor prognosis. The presence of PVTT ...frequently accompanies substantial hypoxia within the tumor microenvironment, which is suggested to accelerate tumor metastasis, but it is unclear how this occurs. Recent evidence has shown that the hypoxia-inducible factor HIF-1α induces epithelial-to-mesenchymal transition (EMT) in tumor cells to facilitate metastasis. In this study, we investigated whether hypoxia-induced EMT in cancer cells also affects immune cells in the tumor microenvironment to promote immunosuppression. We found that hypoxia-induced EMT increased the expression of the CCL20 cytokine in hepatoma cells. Furthermore, coculture of monocyte-derived macrophages with hypoxic hepatoma cells revealed that the expression of indoleamine 2, 3-dioxygenase (IDO) was induced in monocyte-derived macrophages in a CCL20-dependent manner. In turn, these IDO-expressing monocyte-derived macrophages suppressed T-cell proliferation and promoted the expansion of immunosuppressive regulatory T cells. Moreover, high CCL20 expression in HCC specimens was associated with PVTT and poor patient survival. Collectively, our findings suggest that the HIF-1α/CCL20/IDO axis in hepatocellular carcinoma is important for accelerating tumor metastasis through both the induction of EMT and the establishment of an immunosuppressive tumor microenvironment, warranting further investigation into the therapeutic effects of blocking specific nodes of this signaling network.
Improving heteroatomic interactions via alloying or forming heterogeneous catalysts is of importance to the enhancement in terms of electrocatalytic activity and stability. In this work, a simple ...galvanic replacement reaction was utilized to synthesize low Pt-based quaternary nanotubes (NTs). It is easy to obtain PtPdRuTe NTs with different composition and controlled shape using ultrathin Te nanowires (NWs) as sacrificial templates for its high activity. The NT wall thickness and formed NPs on the surface are closely related with the composition, especially Pd content. The optimized incorporation of Pd atoms into ternary PtRuTe NTs formed a uniform protecting PtPd surface and modified the Pt electronic structure to improve the methanol oxidation reaction (MOR) performance. X-ray photoelectron spectroscopy (XPS) reveals a larger extent of electron transfer from neighboring atoms to Pt on PtPdRuTe, consequently leading to a weaker bonding of the intermediate on Pt. As a result, the quaternary PtPdRuTe NTs exhibit enhanced activity and stability toward efficient MOR.
Following the termination of seafloor spreading in the South China Sea (SCS) basin, abundant intraplate volcanism widely spreads in the Indochina block, SCS basin, and Leiqiong area, forming the ...Southeastern Asian Basalt Province (SABP). The geodynamic origin of the SABP has long been enigmatic and debated. Here, we present a high‐resolution 3‐D upper mantle S‐wave velocity model in the region by conducting earthquake‐based surface wave tomography with seismic data collected across Southeast Asia. The resultant images depict a plume‐like structure beneath the central area of the SABP, characterized by a continuous, sub‐vertical low‐velocity column in the upper mantle. Our new findings, combined with previous geochemical and geodynamic evidence, suggest that the extensive post‐spreading intraplate volcanism within the SABP is likely induced by this focused mantle upwelling, which could be further traced down to the core‐mantle boundary as inferred by existing global velocity models.
Plain Language Summary
The well‐known Southeastern Asian Basalt Province (SABP), which covers an extensive area of the South China Sea (SCS) and surroundings, is characterized by voluminous volcanism after the cessation of seafloor spreading in the SCS basin. However, the geodynamic mechanism responsible for the formation of the SABP remains debated and not well understood. In this study, we build a high‐resolution 3‐D seismic velocity model in the region utilizing multiple sources of seismic data collected throughout Southeast Asia. We find a distinct plume‐shaped low‐velocity anomaly in the upper mantle beneath the central region of the SABP. Combining with previous geochemical and geodynamic research results, we interpret that the abundant intraplate volcanism within the SABP may be contributed by the underlying focused mantle upwelling. This mantle upwelling, as evidenced in previous global seismic velocity models, could be further traced down to the core‐mantle boundary (∼2,900 km below the Earth's surface). Our tomographic images provide valuable insights into the origin and mantle dynamics related to the young intraplate volcanism that occurred in Southeast Asia.
Key Points
A high‐resolution 3‐D upper mantle S‐wave velocity model surrounding the South China Sea is constructed
A continuous, low‐velocity column is imaged beneath the central region of the Southeastern Asian Basalt Province
The post‐spreading intraplate volcanism within the Southeastern Asian Basalt Province is likely induced by the focused mantle upwelling
Direct methanol fuel cells (DMFCs) as candidates for dominant energy conversion devices based on the higher energy densities of liquid methanol show unique advantages over hydrogen-based fuel cells, ...such as cheapness and ease of storage and transportation. However, the fundamental challenges for electrochemical oxidation of methanol are the sluggish electro-oxidation kinetics and recovery of Pt surfaces to lower costs. Here, we report a mixed solvent strategy to prepare a highly active and durable class of electrocatalysts with connected single crystalline nanoparticles (NPs), forming an open architecture. Each single crystalline NP along PtCu nanotubes (NTs) can be considered as a highly active unit with specific facet and assembles along one-dimensional (1D) direction. The Pt 1 Cu 1 –AA NTs achieve a factor of 5.5 and 10.3 enhancement in mass activity (2252 mA mg −1 ) and specific activity (6.09 mA cm −2 ) for methanol oxidation reaction (MOR) relative to Pt/C catalysts, respectively. Moreover, after long-term stability tests, the activity of the NTs could be recovered via a simple potential cycling process (reactivation process) to the initial value or better. Thus this kind of catalysts would limit the costs to the initial investment and recovery and show potential possibility in real DMFC devices.
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